61948-ZZ bearing: complete specifications & equivalents

Specification table

Source: catalog reference (NSK Rolling Bearings E1103 Part C) · extracted 2026-09-24

Cross references & equivalents

Interchange levels: full standard interchange · partial verify parameters · verify manual confirmation required. Links resolve to the equivalent model's specification page where available.

How the 61948-ZZ model number is decoded

In the 61900-series (diameter series 9 of ISO 15) the last two digits encode the bore: 61948 carries bore code 48 = 240 mm. Outside diameter 320 mm and width 38 mm come from the ISO 15 boundary-dimensions general plan. Suffix -ZZ denotes two non-contact metallic shields; they retain grease and block coarse debris but are not liquid-tight. For normal-load mounting with a rotating inner ring on a 240 mm shaft, typical catalogue practice is a m6 shaft seat with an H7 housing bore — verify against the actual load direction and magnitude. NSK catalogue order number: 6948ZZ (suffix ZZ), two non-contact steel shields, mapped here from the industry-neutral -ZZ spelling.

Typical equipment & failure modes

Selection pitfalls — read before you substitute

• At 240 mm bore the ring mass is significant: heat 61948 on an induction heater (max 120 °C), never over an open flame, and plan puller access or a withdrawal sleeve now for the day it has to come off again.
• The 619xx thin section (40.0 mm section height at 240 mm bore) trades load capacity for compactness; stiff, accurately aligned seats are essential or edge loading will spall the raceway early.
• ZZ shields are non-contact: 61948-ZZ blocks chips and coarse dust but is not waterproof — do not install it expecting a pressure-wash seal, step up to 61948-2RS for that.
• Shielded 61948-ZZ units are typically greased for life; prying the shields out for regreasing usually bends them and leaves a gap that throws grease in service.
• Deep-groove ball bearings tolerate only minutes of misalignment; if the 320 mm housing cannot be aligned, switch to a self-aligning type rather than shimming 61948-ZZ.
• Vibration during standstill brinells the raceways of a 240 mm bearing at ball spacing; if the machine sits idle next to running equipment, turn the shaft over periodically or isolate the arrangement.
• NSK catalogues the shielded version as 6948ZZ — suffix ZZ, two non-contact steel shields. The industry-neutral page spelling is -ZZ; quote the NSK order number when buying through an NSK channel.
• The 240 mm bore places 61948 at the upper end of NSK's single-row deep-groove catalogue for the E1103 Part C extract; this is a heavy-engineering bearing where centrifugal force and cage inertia dominate the design envelope. NSK supplies a machined brass cage (suffix M) and expects oil lubrication with a defined relubrication interval — do not use catalogue grease speed figures for this size without an NSK engineering review.
• NSK rates 61948 at 170 kN dynamic (C) and 190 kN static (C0); this heavy-load rating is at the upper end of the E1103 Part C single-row deep-groove extract — NSK supplies a machined brass cage (suffix M) and expects an application review, because catalogue L10 life alone does not capture shock and misalignment loads at this rating.
• At 8490 g (8.5 kg), 61948 is a heavy NSK bearing that requires a crane or hoist for handling; induction-heat the inner ring (max 120 °C) and use a mechanical puller for removal — never apply heat directly to the balls or cage.
• The 240×320×38 mm envelope of 61948 gives a D/d ratio of 1.33 and only 40.0 mm radial section height — this is an ultra-thin section in NSK's E1103 catalogue where shaft deflection and housing ovality directly load the ball-raceway contact; verify shaft stiffness (target deflection under 0.05 mm) before specifying it over a 62-series.
• The 170/190 kN load ratings, mass 8490 g here are NSK Rolling Bearings E1103 Part C catalogue figures for 6948ZZ on the 240×320×38 mm ISO 15 envelope; internal geometry and ratings legitimately differ between brands, so re-verify before substituting another manufacturer's 61948 in a rated drive. NSK does not tabulate reference or limiting speeds in the E1103 Part C dimension tables used for this page — consult NSK's separate speed-rating tables before high-speed service.
• NSK's VV non-contact seal keeps frictional torque close to the open 61948; in motor duty where heat build-up matters, VV is the usual compromise between debris protection and speed capability.
• Keep NSK bearings in the original packaging until fitting: the wrapper carries the production lot, and the unopened shelf life of greased sealed units is typically quoted at three to five years in dry, vibration-free storage.